Being physically active has numerous benefits. Now a study has looked closely at the effects of fitness in the midlife years for preventing debilitating chronic diseases later.

The ongoing study gathered fitness stats for more than 18,000 adults, and followed their health status into old age. Assessing 40 years of that data, the analysis finds that those who had higher fitness levels in their 30s, 40s and 50s were substantially less likely to have a chronic condition between the ages of 70 and 85. The findings are in the Archives of Internal Medicine. [Benjamin Willis et al., Midlife Fitness and the Development of Chronic Conditions in Later Life]

Physical fitness seemed to stave off heart disease and heart failure, which might not be a big surprise. But it also reduced rates of diabetes, kidney disease and even Alzheimer's disease.

Current recommendations suggest adults make time for at least 20 minutes of moderate to vigorous physical activity a day, such as fast walking, jogging, biking or swimming. Busy middle-aged people might find it especially hard to make time for such exercise. But a small investment looks like it could pay big health dividends for decades to come.